基于遥感数据的内蒙古草原灌丛物候变化研究

植被物候研究是全球气候变化研究的重要内容,但国际上有关干旱半干旱区灌丛物候变化的研究还很缺乏。为了探讨气候变化对内蒙古草原灌丛物候的影响,利用2000~2011年的MODIS EVI时间序列影像,采用动态阈值法得到6种灌丛12 a物候年际变化情况,结合样点附近气象站的气温和降水数据,分析了灌丛物候与气候变化的动态关系。结果表明：（1）内蒙古中西部草原灌丛返青期、枯黄期都呈现提前的趋势,生长季长度缩短;（2）春季均温升高和前一年秋冬降水增加可以提前灌丛返青期,是影响返青期的主要因素;（3）秋季降水减少和夏秋均温上升都利于枯黄期提前,夏季降水的作用则因灌丛种类不同而略有差异;（4）夏秋均温上升缩短了生长季长度,夏秋降水量、春季均温则多与生长季长度呈正相关。

Variation Characteristics of Shrub Phenology in Grassland of Inner Mongolia Based on MODIS

Vegetation phenology study is an important content on the research of global climate change. But there are few researches about phenological variation of shrubs in arid and semi- arid area internationally. In order to explore the impact of climate change on shrub phenology in grassland of Inner Mongolia,based on the time series images of MODIS EVI from 2000 to 2011,the annual changes of the six kinds of shrub phenology were studied by using asymmetric Gaussian fitting algorithm to acquire dynamic threshold. Meanwhile,the dynamic relationship between phenology of shrub and climate factors including the monthly temperature and precipitation data from nearby weather stations was analyzed. The results showed that：（ 1） the beginning of growing season（ BGS） and end of growing season（ EGS） of shrubs were advancing,while the length of growing season（ LGS） was shortening.（ 2） the rising average temperature in spring,increasing precipitation in last autumn and winter would be to the benefit of BGS of shrubs in advance.（ 3） the reducing autumn precipitation and rising average temperature in summer and autumn were propitious to advance EGS,however the effects of summer precipitation on EGS had a slightly difference for different species of shrub;（ 4） the rising temperature in summer and autumn shortened LGS,and the precipitation in summer and autumn and average temperature in spring mostly showed a positive correlation with LGS.